Install guide

3.2. Storage Topology
Once the server has all the required software installed, configuration can commence. Configuring the
server node to map the external LUN will require some incremental configuration on the server, some
incremental configuration on the array and then back to the server to verify that all LUNs were mapped.
Since the storage pathways will be multipathed, all LUNS must be visible down both ports on the HBA
before moving onto the multipath configuration.
3.2.1. HBA WWPN Mapping
Fiber Channel HBAs typically have two ports or, for extra redundancy, two single-ported HBAs are
deployed. In either case, the World-Wide Port Number (WWPN) for each port must be acquired for both
nodes and used to register the LUNS so the storage array will accept the connection request. Try to
install the FCP ports into the server before RHEL is installed. T his will insure they are configured for use,
once the install is complete.
When FCP switch zones are deployed to isolate database traffic to a specific set of FCP array ports on
the array, the switch will identify the ports physically, or you can also use the specific WWPN. Most
storage administrators know how to do this, but this is what must happen to make sure two copies of the
LUNS show on each server node.
The storage array typically bundles the LUNS that are reserved for this cluster into an initiator group,
and this group list must contain all four WWPNs so that all four requesting HBA ports can see the set of
LUNS.
On RHEL, the easiest place to look for the HBA WWPNs is in the /sys directory, but the switch often has
logged the port names as well, so you can look there if you know how the HBAs are connected to the
switch.
$ cat /sys/class/block/fc_host/host0/port_name
0x210000e08b806ba0
$ cat /sys/class/block/fc_host/host1/port_name
0x210100e08ba06ba0
Use the hex values from the /sys inquiry. Do not use the WWNN or node name. WWPNs needed to be
added to the initiator group on the array, and to the appropriate zone on the switch. Once these steps
are complete, reboot the server and you should see two sets of identical LUNS. You cannot proceed to
the multipath configuration section until there are two identical sets.
3.2.2. Multipath Configuration
The software feature Device-Mapper Multipath (DM-Multipath) was installed as part of the kickstart and
is used to provide pathway redundancy to the LUN. Configuring DM-Multipath must be the next step.
Both the Red Hat Cluster Suite quorum disk and the Oracle Clusterware support disks will need to use
the resulting DM-Multipath objects. Once DM-Multipath is configured, the block device entries that will be
used appear in /dev/mapper.
The installation of DM-Multipath creates an rc service and a disabled /etc/multipath.conf file.
The task in this section is to create reasonable aliases for the LUN, and also to define how failure
processing is managed. T he default configuration in this file is to blacklist everything, so this clause
must be modified, removed, or commented out and then multipath must be restarted or refreshed. Be
sure the multipah daemon is set to run at reboot. Also, reboot of the server should take place now to
ensure that the duplicate sets of LUN are visible.
To create aliases for LUNs, the WWID of the scsi LUN must retrieved and used in the alias clause. T he
Red Hat Enterprise Linux 5 Configuration Example - Oracle HA on Cluster Suite
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